The present invention relates to restorative dentistry and especially to provisional dental restorations for human teeth.
Porcelain and porcelain-metal dental restorations such as veneers, crowns, inlays and onlays are often used to correct or reconstruct the length, size, shape, alignment, occlusion or color of teeth. The use of porcelain restorations provides several advantages, including life-like appearance and superior wear resistance. However, porcelain restorations cannot be prepared by the dentist, but must be fabricated by laboratories, which significantly increases the time and expense involved. Furthermore, porcelain restorations are often difficult to work with, due to the thinness and fragility of the material.
Thus, temporary or provisional restorations made of composite resins are often prepared by the dentist to assess fit and appearance before fabricating definitive porcelain restorations. These provisional restorations also provide the patient with an aesthetic substitute in the interim, while the porcelain restoration is being fabricated by the laboratory.
Methods of preparing provisional restorations using composite resins are well known in the art. For example, in the case of provisional veneers, such methods involve taking a pretreatment impression of the teeth-receiving provisional veneers to create an impression matrix that serves as a template for preparing the provisional veneers. Once the impression matrix has been formed, the teeth-receiving provisional veneers are prepared by reducing the teeth, using the impression matrix as a check to ensure that there is adequate clearance between the prepared tooth and the impression matrix.
The shells of the impression matrix corresponding to the teeth-receiving provisional veneers are filled with a light-curable flowable composite resin and then seated over the prepared teeth. The composite resin is light-cured through the impression matrix, which is then removed to reveal the provisional veneers.
One shortcoming to such prior art methods of preparing provisional veneers is that, as the filled impression matrix is seated over the prepared teeth, excess composite resin is expressed into the gingival margin of the prepared teeth and over adjacent teeth and gum. Upon curing, the excess composite resin forms a flash covering the gingival margin of the prepared teeth, as well as the adjacent teeth and gum.
To avoid initiating marginal gingivitis, this flash must be removed and the cervical finish line of the provisional veneer very accurately adapted to the prepared teeth at the gingival margin. However, removal of this flash requires the use of aggressive finishing burs and is almost impossible to accomplish without damaging the cervical finish line or gingival tissue at the gingival margin. Furthermore, flash below the gum line is inaccessible and cannot be effectively removed. In addition, the removal of flash also involves the risk of nicking or otherwise damaging adjacent teeth.
Thus, there is a reluctance to disturb the provisional veneers at the gingival margin, and provisional veneers are typically left with overhangs at the cervical finish line, which invariably results in marginal gingivitis. This is a highly undesirable condition to have present during the subsequent cementation of the definitive porcelain veneers.
Another problem with such prior art methods is that the resulting provisional restorations cannot accurately reproduce the polychromatic color gradation of natural teeth. Typically, the cervical portion of natural teeth has a darker color shade than the incisal portion. Because the provisional restorations are prepared from a single composite resin, they are uniformly colored and may appear artificial.
Thus, it would be desirable to provide a method for preparing provisional restorations in which the cervical finish line of the provisional restoration may be accurately adapted to the prepared teeth at the gingival margin, without risk of damage to the cervical finish line or gingival tissue at the gingival margin, or to adjacent teeth and gums. In addition, there is a need for a method of preparing provisional restorations that accurately reproduces the natural variation in color between the cervical and incisal portions of teeth.
These needs and other needs are satisfied by the present invention, which comprises a method for preparing provisional restorations, wherein an impression matrix of the teeth-receiving provisional restorations is prepared using a translucent, clear-colored impression material. The teeth receiving provisional restorations are then prepared by reducing the teeth, and applying a dental adhesive to the surface of the prepared teeth.
The impression matrix is then trimmed such that the cervical portion of the prepared teeth is exposed when the impression matrix is fully seated over the prepared teeth. The shells of the trimmed impression matrix corresponding to each of the prepared teeth are filled with a light-curable flowable composite resin, which will form the incisal portion of the provisional veneers. The filled impression matrix is then seated over the prepared teeth, the excess light-curable flowable composite resin is removed from the exposed cervical portion of the prepared teeth, and the remaining light-curable flowable composite resin cured through the translucent, clear-colored impression matrix.
The impression matrix is removed to reveal the newly formed incisal portion of the provisional veneers. A light-curable sculptable composite resin is applied to the cervical portion of the prepared teeth and free-form sculpted to form the cervical portion of the provisional restorations. The sculptable composite resin is then light cured and the provisional restorations completed by fine-finishing and polishing.